1. Field of the Invention
The invention relates to an information recording medium, and more particularly, to a recording and/or reproducing apparatus, a recording and/or reproducing method, a disk manufacturing apparatus and method, and/or an information recording medium.
2. Description of the Related Art
A channel bit length (CBL) of a digital versatile disk (DVD) is presently 0.133 μm. As the density of data storage in a DVD increases, the width and CBL of the DVD track decrease. As a result, the capability to correct an error decreases. The decrease in the error correction capability due to the decrease of the CBL can be compensated for by increasing the size of a recording and/or reproducing block, for example, by increasing the size from 32 KB to 64 KB. Thus, increasing the size of a recording and/or reproducing block to compensate for the decrease in the error correction capability is a preferable method for detecting errors in 80-mm or 120-mm disks. However, as the physical size of a recording medium continues to be reduced, a start radius, which is a start line for recording data, decreases, and accordingly, there exist some areas where the circumference of a data recording area is shorter than the length of a recording and/or reproducing block.
FIG. 1 is a diagram showing a scratch occurring in an overlapping area when the length of a recording and/or reproducing unit block or an error correction code (ECC) block exceeds one circumference according to a conventional method.
As shown in FIG. 1, when the circumference of an area where data are recorded is shorter than the length of a recording and/or reproducing unit block, the length of one block is longer than one circumference such that an overlapping area occurs, and if a scratch is made in this overlapping area, the error correction capability decreases, causing a reliability problem.
More specifically, on a disk-type recordable information recording medium, data is recorded along a track of the information recording medium, from an inner circumference to an outer circumference or from an outer circumference to an inner circumference. If the length of one recording and/or reproducing unit block or one error correction code (ECC) block is longer than a circumference with respect to a radius (or a diameter) of the information recording medium, an overlapping part of the recording and/or reproducing block or the ECC block in the radius direction occurs. Also, an error caused by dust, scratch, fingerprint, etc., usually affects many adjacent tracks. Accordingly, the effect of an error in the overlapping part is doubled in one ECC block and greatly reduces the reliability of the data.
FIG. 1 is a diagram showing a scratch occurring in an overlapping area. For example, as can be seen with reference to FIG. 1, when a 1 mm scratch is made in the overlapping area in the track direction, the practical effect to one ECC block is the same as when a 2 mm scratch occurs.
In case of a Reed-Solomon Product Code (RSPC) of a DVD, the code is formed with 416 sync frames, including 32 KB of user data, and one sync frame has 1488 channel bits. Referring to DVD specifications, details on this can be obtained. A detailed description of DVD specifications is readily and easily obtainable and will not be discussed herein.
Since the length of one channel bit is 0.133 μm, the length of one recording and/or reproducing block in the track direction is 416*1488*0.133 μm=82,328.064 μm.
Since 82,328.064 μm/3.14 equals approximately 26,219.129 μm, a circumference having a radius of less than approximately 13.1 mm is shorter than the length of the recording and/or reproducing unit block. Since the length of one sync frame=1488*0.133 μm=197.904 μm, a scratch of 1.6 mm affects about 8 continuous sync frames. In this case, an error of 4 bytes is caused in the Reed-Solomon (RS) (208,192,17) code in the length direction (case 1). When a scratch is made in the overlapping part, an error of 8 bytes, which is double the size of the error of case 1, is caused in the RS (208,192,17) code in the length direction (case 2).
Assuming that erase correction is performed for a location where a scratch occurs, when a byte error rate is 10−3, the error correction capability of the RS (208, 192, 17) code in the length direction is calculated by the following equation 1:
                    CER        =                  1          -                                                                      Q                                      i                    =                    0                                                                                        (                                          16                      -                      e                                        )                                    /                  2                                            ⁡                              (                                                                                                    208                        -                        e                                                                                                                        i                                                                      )                                      ⁢                                          E                ⁡                                  (                                      1                    -                    p                                    )                                                            208                -                e                -                i                                      ⁢                          Ep              i                                                          (        1        )            
Here, CER denotes a Codeword Error Rate, e denotes Erase number, and p denotes Byte Error Rate. When the CER is calculated for case 1 using the equation 1, since p=0.001 and e=4, the CER=2.2×10−9. When the CER for case 2 is calculated, since p=0.001 and e=8, the CER=2.2×10−6.
In case 2, when double errors by a random error, such as a small dust, occur in the overlapping location, the errors are not considered. Thus, the effect of a scratch in an overlapping part is critical to the reliability of data. Though the RSPC has an error correctible structure, the degradation of the error correction capability of the code cannot be ignored. In a DVD environment, the maximum error correction length of the RSPC is approximately 6 mm.
However, when recording and/or reproducing unit data is stored in an area longer than a circumference, for example, when data is recorded in a radius of 7 mm, one RSPC block exists along almost two tracks such that the maximum error correction length is reduced to 3 mm.
Thus, when a circumference of an area where a recording and/or reproducing unit block is recorded is shorter than the length of the recording and/or reproducing unit block, an overlapping area occurs and the error correction capability is substantially reduced such that the reliability of the data is reduced.
Examples of address data generated in an information recording medium are discussed below.
FIGS. 2A through 2D are diagrams explaining the address structure of an ADress In Pregroove (ADIP) which is recorded as a wobbling groove according to a conventional method.
FIG. 2A is a diagram showing an ADIP-recording unit block (RUB) data frame as an example of using ADIP address recorded as a wobbling groove. One recording unit block (RUB), that is, a recording cluster, is 498 frames. The recording unit of 498 frames is obtained by adding a run-in and a run-out for linking to 496 frames as the ECC block of data. As shown in FIG. 2A, 3 address blocks as ADIPs are included in an interval corresponding to one RUB. One address block is formed with 83 bits. An 83-bit address block includes an 8-bit sync part (a synchronization signal part) and a 75-bit data part.
In the 8-bit sync part, 4 units of sync blocks, each unit comprising a monotone bit (1 bit) and a sync bit (1 bit), are formed. In the 75-bit data part, 15 units of ADIP blocks, each unit comprising a monotone bit (1 bit) and ADIP bits (4 bits), are formed.
FIG. 2B is a diagram showing a detailed frame structure of a sync part of an address block (ADIP) of FIG. 2A.
An 8-bit sync part is formed with 4 sync blocks. Each sync block is 2 bits long.
Sync block “0” is formed with a monotone bit and sync “0” bit. Sync block “1” is formed with a monotone bit and sync “1”. Sync block “2” is formed with a monotone bit and sync “2”. Sync block “3” is formed with a monotone bit and sync “3”.
FIG. 2C is a diagram of a detailed frame structure of a data part of an address block (ADIP) of FIG. 2A.
A data part is formed with 15 ADIP blocks. Each ADIP block is 5 bits long. Each 5-bit ADIP block is formed with 1 bit of a monotone bit and 4 bits of ADIP bits.
Referring to FIG. 2C, address information is 60 bits long in the 75-bit data part excluding 15 bits of monotone bits. The structure of this 60-bit address information is shown in FIG. 2D.
Referring to FIG. 2D, 60-bit address information includes an address part, a reservation part, and a parity part.
Thus, when the circumference of an area where a recording and/or reproducing unit block is recorded is shorter than the length of the recording and/or reproducing unit block, an overlapping area occurs and the error correction capability is substantially lowered such that a problem of reliability of data can be caused.